MOLECULAR AND CYTOGENETIC STUDIES OF HUMAN CELL AGING

正常人体细胞在体外表现出严格的分裂限制 容量。相比之下，肿瘤来源和病毒、致癌物或 辐射转化的细胞可以无限分裂(永生)。我们有 还不了解限制除法潜力的机制 正常的人类细胞或产生永生细胞的变化。 然而，从细胞杂交研究中我们发现，不朽的 表型是正常细胞生长控制中隐性变化的结果。 我们利用这一事实分离出了24个不同的神仙 细胞系分为四个互补群，进行无限分裂。 这表明至少有四种途径可以长生不老 至少有四个或四组基因与正常细胞生长有关 控制力。利用微细胞介导的染色体转移技术， 我们已经确定，引入正常的人类4号染色体 分成三个永生的人类细胞系，分配给互补组 B，导致失去增殖。这是对 B组细胞系，因为永生细胞的分裂能力 分配给其他组的品系不受该染色体的影响， 而正常的11号染色体对任何永生细胞都没有影响 线路测试。这些结果表明细胞存在衰老现象。 人类4号染色体上的相关基因(S)。我们还发现了一个正常的 1号染色体导致一个永生人类细胞失去增殖能力 分配给C组的线路，在此提案中，我们计划采取 多管齐下克隆4号染色体上的基因并研究 其在衰老和永生化过程中的表达调控。我们 也将决定1号染色体是否影响细胞的增殖 分配给C组的其他永生人类细胞系的潜力 确实如此，这将表明另一个细胞衰老基因(S)是 存在于此染色体上，我们将尝试将该区域定位在 涉及到的1号染色体。

Normal human cells in vitro exhibit a stringent limitation of division capacity. In contrast, tumor-derived and virus-, carcinogen- or irradiation-transformed cells can divide indefinitely (immortal). We do not yet understand the mechanisms that limit the division potential of normal human cells or the changes occurring to yield immortal cells. However, from cell hybrid studies we have found that the immortal phenotype results from recessive changes in normal cell growth control. We have exploited this fact to separate twenty four different immortal cell lines into four complementation groups for indefinite division. This indicates that there are at least four paths to immortality and that at least four genes or sets of genes are involved in normal cell growth control. Using the technique of microcell mediated chromosome transfer, we have determined that the introduction of a normal human chromosome 4 into three immortal human cell lines that assign to complementation group B, results in loss of proliferation. This is a specific effect to the group B cell lines, because the division capability of immortal cell lines assigned to the other groups is not affected by this chromosome, and a normal chromosome 11 has no effect on any of the immortal cell lines tested. These results indicate that there is a cell senescence related gene(s) on human chromosome 4. We have also found that a normal chromosome 1 induces loss of proliferation in one immortal human cell line that assigns to group C., In this proposal, we plan to take multipronged approaches to clone the gene on chromosome 4 and study regulation of its expression during senescence and immortalization. We will also determine whether chromosome 1 affects the proliferation potential of other immortal human cell lines that assign to group C. If it does, this would indicate that another cellular senescence gene(s) is present on this chromosome and we will attempt to localize the region on chromosome 1 that is involved.